Few words strike fear into the hearts of longtime married couples like the phrase “family vacation.” In terms of terrors, it ranks right up there with “my mother is coming to live with us.”

It’s not that family vacations are in and of themselves bad; it’s that they’re perfect opportunities for disaster.

Families are a biological fact. Two people get together and produce children — anywhere from one to a hundred. Not all of these unions end well, but, for our purposes today, we’re talking a family with a dad, mom, assorted children and maybe a dog.

To provide their offspring with meaningful family experiences — and sometimes to clue them in to the fact that their genetic horror isn’t relegated to the confines of one home — family vacations are sometimes taken in conjunction with larger family reunions.

Wife • “My family is having its annual reunion this year in Pahrump. Instead of spending a bunch of money on Disney World, let’s go there.”

Husband • “That’s a great idea. You know what would be cheaper and even more fun? If we went outside and you ran over me with the car a hundred times.”

Just because your spouse loves and wants you doesn’t mean that she or he regards the rest of your family as anything more than feral hogs.

If you want to have a good family vacation this year — or want next year’s to end on a better note than jail — consider these cost- and sanity-saving steps.

Step No. 1 • Don’t automatically expect that your significant other will regard spending a week with your family as relaxing. There could be a good reason you live so far away.

Every family, including yours, has someone in it who is homicidally annoying. In my family — as you’ve no doubt guessed — that’s me, which probably explains why we receive so few visits from my wife’s relatives.

Put us in the same resort, campground or cabin longer than 30 minutes, and someone is going to get felony butt-hurt.

Step No. 2 • Wherever you decide to go on family vacation, make sure everyone actually wants to go. This includes those you might expect to have no say in the matter.

Tell your 9-year-old boy that family vacation this year will be spent museum hopping in Washington, D.C., instead of at the beach, and see how much he has to say about it by the third museum. It’ll live on in family legend as “the summer of Dad’s nervous breakdown.”

Step No. 3 • Leave as little to chance as possible. I can’t point to it exactly, but somewhere in the Bible it says, “Wherever two or three are gathered with the same last name, there is lunacy in the midst of them.” Look it up if you don’t believe me.

So, do not take anyone on vacation whom you are not prepared to leave on the side of the road or in a foreign air terminal when things go bad.

Step No. 4 • Make sure ALL bring an ample supply of their prescribed psych meds. In fact, put the drugs in a Ziploc bag and staple-gun them to their foreheads.

You don’t want to be in East Asia and have someone run out of their antipsychotic meds. From personal experience, you don’t want to be at Utah Lake when that happens either.

Step No. 5 • Water, food, sleeping gear, duct tape, knife, first aid, bug repellant — all of that stuff is important. But, most of all, bring patience. You’re going to need it.

Finally, my family and I are going on vacation this month. You might want to stay home during that time. A family vacation is no respecter of innocent bystanders.